Dark Sun: The Making Of The Hydrogen Bomb

agreement that agglomeration to detectable size was at least possible. Experiment would test the calculations; preparations for Sandstone were then underway.

AFOAT-1 had the sense to mount the experiment even though the Sandstone tests were all tower shots and therefore dirty — their fireballs would reach the ground and scoop up debris. Sniffer planes equipped with fuselage ducts that scooped air through paper filters flew below the jet stream thousands of miles from Eniwetok and collected fallout. Even the scientists at Tracer lab were surprised by what they found — “not only particulate matter [i.e., dirt particles] but [also] matter in terms of shiny metallic-looking spheres that were just beautiful.” The microscopic metallic spheres were radioactive agglomerations of gasified atoms from the Sandstone bombs. By July 1948, the Air Force was able to tell the AEC that it “was confident of being able to detect by radiological means an atomic air burst.” By January 1949, when the Air Force briefed Strauss on its program, it was running regular sniffer flights on its own, and Strauss could report to Forrestal that “the door is no longer left unguarded.”

Oppenheimer was still unhappy, however. He speculated that the Soviets might conduct their tests underground to avoid releasing telltale radioactivity and wanted AFOAT-1 to develop a seismic detection system before it officially deployed its network. Strauss added Oppenheimer's resistance to relying on radiological detection alone to his list of suspicions, concluding that the mercurial physicist was trying to thwart long-range detection. It was not the first time Oppenheimer, a man who jumped to finish other people's sentences, had outsmarted himself. When Luis Alvarez had carried the news of nuclear fission to Oppenheimer at Berkeley in January 1939, the theoretician's first response had been to tell Alvarez, “That's impossible” and to give Alvarez “a lot of theoretical reasons why fission couldn't really happen. When I invited him over to look at the oscilloscope later, when we saw the big pulses [of ionization from fission], I would say that in less than fifteen minutes Robert had decided that this was indeed a real effect and… that you could make bombs and generate power… It was amazing to see how rapidly his mind worked, and he came to the right conclusions.” But first, as later in the matter of agglomeration and long- range detection, Oppenheimer got it wrong.

To enlarge its reach, the Air Force had decided after Sandstone to let the British in on the secret detection program, which required working around the Atomic Energy Act. The US Navy also began developing a ground-based system that included collecting rainwater off the roof of the Naval Research Laboratory in Washington, DC. By the time the Air Force began flying sniffer planes out of Alaska for the AFOAT-1 program in April 1949, the British were in business over the North Atlantic and the Navy was filling rain barrels and scanning for gamma radiation in Alaska, the Philippines and Hawaii as well as in Washington. Between April and August, the WB-29s of the 375th Weather Reconnaissance Squadron trapped radioactivity on their filters greater than the natural background a total of 111 times. The suspect filters went to Tracerlab in Berkeley, which dissolved them, chemically separated a selection of fission products such as radioactive isotopes of barium, cerium, molybdenum, zirconium and lead, carefully measured the rates of radioactive decay of the isotopes and counted back to establish when each isotope had been created — its radioactive birthday. Only if all the birthdays were identical could the isotopes have been created in an atomic bomb. The 111 samples all turned out to be natural in origin, released from the earth (where the spontaneous fission of uranium creates fission products with randomly different birthdays) by earthquakes and volcanoes. But they gave Tracerlab the opportunity to perfect its techniques.

AWB-29 flying east of the Kamchatka Peninsula picked up radioactivity on September 3, 1949. The Kamchatka filter paper showed activity 300 percent greater than the level Tracerlab had established as an alert; measurements quickly confirmed that the radioactivity was fission-derived. Off went the paper to Berkeley. “More evidence came in over that weekend,” writes GAC secretary and Los Alamos associate director John Manley. “During the next week the radioactive air mass was followed across the [US].” A physicist at Tracerlab remembers measuring radioactivities “night and day for a period of two weeks. I didn't sleep more than four hours a day. Our little group was working around the clock.” The AEC alerted the British on September 9 that the air mass was approaching England. Routine sniffer flights out of Gibraltar and Northern Ireland before that notice had found no radioactivity, so the British sent a Halifax bomber north from Scotland on the evening of September 10 and followed up the next morning with several Mosquitos that sniffed along the Norwegian coast. These explorations quickly confirmed radioactivity. In the meantime, the Navy had flocculated rainwater from the roof of its Washington laboratory and further confirmed the Air Force findings. “The ‘cloud’ which drifted over the Pacific and the US,” a JCAE staff member would note of the Navy's operation, “split up over midwestern Canada, the southern part of the cloud drifted down over Washington and hung there for two or three days, during which the rain brought down the material. The northern part of the ‘cloud’ traveled on out over the Atlantic where it was detected in Scotland by the English.”

“By September 14,” Manley continues, “95 percent of the experts analyzing the data were convinced [that the samples represented bomb debris] and had dubbed the event ‘Joe One’ after Stalin.”[33] Los Alamos estimated an explosion no more than thirty days prior to September 13; the Navy and the British came within a week on each side of the actual date. Tracerlab, with a cleaner lab and more practice teasing information out of microscopic samples, estimated the Soviet explosion to have taken place at 0000 Greenwich Mean Time on August 29 — six a.m. in Semipalatinsk, only an hour off the actual event. The commercial laboratory also established that the bomb used a plutonium core and a natural uranium tamper.

Secretary of Defense Louis Johnson refused to believe the expert ninety-five percent, however. “I recall going with [William] Webster [chairman of the Military Liaison Committee] to see Secretary Johnson,” Kenneth Nichols said many years later. “Bill was telling him that we had intelligence that the Russians had exploded an atomic bomb. The Secretary sort of pooh-poohed the idea. He said, T don't believe too much in intelligence.’ I remember I spoke out of turn, I said, Well, Mr. Secretary, you better get ready to believe this one. It's not of the creep type [of intelligence], it's firm.” Johnson's doubt settled on the possibility that a Soviet reactor might have exploded and he refused to authorize a public announcement. Truman knew of the technical intelligence by now but was not prepared to overrule Johnson. The AEC responded by assembling an expert committee under Vannevar Bush, the wartime US science czar, that included Robert Oppenheimer; William Penney, the English physicist who was directing the British bomb program; physicist and former AEC commissioner Robert Bacher; and Hoyt Vandenberg. The committee concluded on September 19 that the Soviets had exploded an atomic bomb, which confirmed the AEC in its conviction that the event ought to be made public as soon as possible. The AEC commissioners decided the same day that Lilienthal should carry the AEC case past Louis Johnson to Truman and win the President's agreement.

Exhausted by his summer of battles with Hickenlooper, Lilienthal had retreated to Martha's Vineyard to rest (and had made up his mind to resign). The AEC sent General James McCormack, Jr., its Director of Military Application, off to New England in a C-47 to fetch Lilienthal. Returning from dinner in Edgartown in a Vineyard fog at eleven that Monday night, Lilienthal encountered McCormack hatless in the middle of the road, pretending to thumb a ride, “as if I frequently found him on a windswept moor, in the dead of night, on an island, outside a goat field… No questions; said he had lighted a candle in our house. Had he parachuted; what was this?” Inside, “General Jim” gave Lilienthal the news, by the light of a kerosene lamp.

The AEC chairman flew to Washington the next morning, September 20, to find Bacher “deeply worried,” Oppenheimer “frantic, drawn,” but also characteristically “positive [of the evidence for a Soviet test], unequivocal.” Lilienthal slipped through the White House back entrance a little before 3:45 p.m. and encountered an Oval Office scene out of a genre painting: “The President was reading a copy of the Congressional Record, as quiet and composed a scene as imaginable; bright sunlight in the garden outside, the most unbusy of airs. Started talking about it… ” Truman gave Lilienthal a long list of political reasons why he was not yet ready to announce a Soviet bomb, but his basic argument seemed to be that he doubted the intelligence. “German scientists in Russia did it,” Lilienthal paraphrases him at one point, “probably something like that.” At another: “Can't be sure, anyway. I stepped into that: [it] is sure, substantial… Really? — sharp look, question… ” Gordon Arneson, the State Department AEC liaison, remembered getting a call from the National Security Council's Sidney Souers, who was close to Truman, when the news had first reached the White House:

Admiral Souers… called me urgently on the telephone and said: “Come over right away. I have some ‘hot’ intelligence.” It was a beautifully bright fall day in Washington, the kind that makes you glad you were alive whatever the day's news. But as I walked over to Old State, I had a premonition — “This was it.”… Admiral Souers expressed the idea that the radioactive cloud might have come from an accident, a blow-up of a nuclear reactor. I told him I hoped he might be right but it seemed unlikely.